Multi Pixel Photon Counters (MPPC) and Scintillating Fibers (Sci-Fi) as a trigger system for the AMADEUS experiment Alessandro Scordo (L.N.F.) (in behalf of AMADEUS experiment) 23° Indian-Summer School of Physics & 6° HADES Summer School 2011

Contents The AMADEUS experiment: a brief introduction Trigger system requirements MPPC working principle and status of art 10 channels prototype and MPPC characterization Results of tests on DAFNE New electronics and 64 channels prototype Tests on hadronic beam Conclusions

The AMADEUS experiment: a brief introduction KLOE - The main aim of AMADEUS is to confirm or deny the existance of Kaonic Clusters, - EXTENDED PROGRAM: Low-energy interactions, cross sections in light nuclei, decay of resonance states and exotic channels in nuclear medium will be studied DAΦNE

The AMADEUS experiment: a brief introduction Deeply Bound Kaonic Nuclear States First suggested by S.Wycech (1986) Y.Akaishi and T. Yamazaki (Phys. Rev. C65 (2002) 044005) “Nuclear bound states in light nuclei” Normal Nuclear binding energy parameters: Ebind ~ 20 MeV G ~ 100 MeV DBKNS binding energy parameters: Ebind ~ 100 MeV G ~ 30 MeV New kind of matter with astrophysical implications (Neutron stars, prof. Heuser talk) K- + 4He reaction (3-barionic state)

The AMADEUS experiment: a brief introduction

The AMADEUS experiment: a brief introduction Target: A gaseous He target for a first phase of study First 4p fully dedicated setup!

The AMADEUS experiment: a brief introduction

Trigger system requirements Small dimensions Working in magnetic field Working at room temperature Very good time resolution (s ~ 300 ps) High efficiency Trigger system requirements Multi Pixel Photon Counters (MPPC)

MPPC : working principle P-N junction array working in Geiger mode (micropixel) Output signal is the sum of all the micropixels Each micropixel gives a high gain signal (105 – 106) indipendent of the number of incident photons and has a fixed amplitude (binary mode)

First prototype and MPPC characterization Is cooling needed ? A scintillating fiber is activated by a beta Sr90 source Both ends are coupled to detectors; one is used as trigger

First prototype and MPPC characterization Studying rates with and without the beta source, it turned out that starting from the 4th p.e. peak, dark count contribute is negligible This means that non cooling is needed in this case!!!!

Montecarlo simulations: what are we expecting? Momentum distribution of kaons is taken from Kloe Monte Carlo BCF-10 1mm diameter Kaons are expected to leave almost a factor 7 more energy than MIP electrons GEANT3 simulation

Results of tests on DAФNE 22-24 January 2009

Results of tests on DAФNE

Results of tests on DAФNE KM scintillator at 6 cm from Interaction Point Fibers 5 cm below the lowest scintillator RF/2 and KM coincidence as DAQ trigger Pure KM signal also collected MIPs coming from the I.P. are below the KM threshold

Results of tests on DAФNE Kaon Monitor TDC (upper/lower coincidence) Single peak resolution Is ~ 100 ps MIP/K separation ~ 1 ns K- MIPs MPPC tdc spectra Single peak resolution Is ~ 300 ps Missing MIPs

New electronics and 64 channels prototype 32 Sci-Fi read at both sides 2 indipendent double layers with adjustable angle Amplification of a factor 10 64 Constant Fraction Discr. Logic OR of all detectors

Tests on hadronic beam p,m,e-,p beam (similar to DAFNE situation) pM-1 beam at Paul Scherrer Institute (PSI, Zurich) Single particle conditon (to be further checked) Double anular setup 1 3 2 4 DAQ trigger: Sc1&Sc2 Scintillator 1 Scintillator3&2

Common cuts for the whole analysis Tests on hadronic beam Protons Cut fot T > 31.0 C MIPs Common cuts for the whole analysis

Tests on hadronic beam Left Right Perfect correlation and coupling Sc1 is used as reference

Tests on hadronic beam: efficiency 73% Fiber 5: eff = 99 % 92% 90% 70% Fiber 6 : eff = 98,4 % Double layer efficiency Single layer efficiency

Tests on hadronic beam Beam profile Geometrical correlation

Tests on hadronic beam: cross talk Fired fibers of layer 4 if fiber i of layer 4 is fired 4,6% 2% 2,4% 5,2% 6,5% 2% 1% 0,06%

… Conclusions… …and future plans Small dimensions Working in magnetic field Working at room temperature Very good time resolution (s ~ 300 ps) High efficiency … …and future plans Temperature feedback circuit implementation New efficiency measurements with scintillators New tests in DAFNE New ideas and applications for this nice setup

Spare slides

MPPC : working principle Thermally generated electrons can activate the avalanche process in some pixel, with a high rate of 105-106 Hz (dark current) The main contribute is a peak corresponding to 1 pixel (photoeletron)‏ Luminescence of carriers can also be absorbed by another pixel giving a noise signal

First prototype and MPPC characterization Pre-Amplifiers (X 100)‏ 5 Channles HV power supply (stability better than 10 mV)‏ Scintillating fibers Bicron BCF-10 (blue)‏ SiPM (HAMAMATSU U50) (400 pixels)‏ Operating voltage ~70V Sr90 beta source (37 MBq)‏

First prototype and MPPC characterization Threshold at 5 p.e. Peak with most counts: 5 p.e. (15%) Black spectra are the trigger-used MPPC Red spectra are the signal outputs of the NON trigger MPPC

New electronics and 64 channels prototype s ~ 80 ps s ~ 40 ps MPPC + Sci-Fi Direct laser on MPPC

New electronics and 64 channels prototype Fiber Laser HV MPPC RF Preamp Coincidence TDC RF/n RF=90 MHz (≈ RF/4) n ≈ 10000 s ~ 200 ps No jitter from photon generation (to be considered)

Tests on hadronic beam: “relative” efficiency Fiber 5: eff = 27,3 % In the case of non parallel double layers the geometrical efficiency is drastically reduced Fiber 6: eff = 30,1 %

Tests on hadronic beam: “relative” efficiency Fiber 5: eff = 27,3 % In the case of non parallel double layers the geometrical efficiency is drastically reduced Fiber 6: eff = 30,1 %

Single particle configuration ! Tests on hadronic beam: “relative” efficiency Proton events = 6580 Proton on fibers = 1772 Nhits on fibers > 5 = 29 (1,6%) Single particle configuration !